This invention relates to an air cooled vacuum producing condenser of the evaporative type in which the cooling effect is obtained primarily from the evaporation of water directed onto the exterior of a bundle of condenser tubes arranged in an airstream passing over the tubes.
The invention is an improvement of the condenser shown and described in my U.S. Pat. No. 3,148,516 dated Sept. 15, 1964.
This invention is particularly adapted for relatively large capacities as may be required for condensing the exhaust of steam turbines.
Generally, the present invention eliminates prior sumps as part of the condenser shell and provides a basin which drains as it receives water directed over the bundle of condenser tubes. The basin guides the airstream passing over the tubes smoothly through a 180.degree. turn to exhaust the air out of the condenser chamber while preventing entrainment of water by the exhausted air. Thus, a heavier water cascade over the tube bundle is permitted to maintain the external tube surfaces clean and enhance the transfer of heat.
Other novel features will be apparent from the following detailed description, including a new and improved demister screen and a mechanical vacuum pump utilizing cooling water which also provides a partial replacement of the amount of water evaporating from the water cascade.
An object, therefore, of the present invention is to provide a new and improved air cooled vacuum producing condenser of the character described.
In the exemplary embodiment of the invention, a shell is provided having a generally horizontal condenser chamber. A bundle of condenser tubes is disposed generally horizontally across the condenser chamber. An inlet header is disposed at the inlet end of the bundle of condenser tubes, and a condensate outlet header is disposed at the outlet end of the bundle of condenser tubes. The inlet and outlet headers have portions projecting above the bundle of condenser tubes. A bundle of gas devaporization tubes extend across the condenser chamber and connect the portions of the inlet and outlet headers above the bundle of condenser tubes. Means are provided for directing water downwardly onto the bundle of condenser tubes. Means also are provided for discharging air from the interior of the shell to create a downward flow of air through the condenser chamber across the bundle of condenser tubes.
One feature of the invention includes a demister screen across the interior of the condensate outlet header through which the mixture of vapor and gas is required to pass before entering the bundle of gas devaporization tubes. The screen includes a first portion extending generally horizontally from the condenser chamber at a location between the condenser tubes and the gas devaporization tubes, and a second portion extending diagonally downwardly from a distal end of the first portion across the interior of the condensate outlet header. The portion of the inlet header which is connected by the gas devaporization tubes comprises a separate interior chamber portion of the inlet header, and a drain is provided therefrom to at least one of the condenser tubes for any accumulated condensate from the gas devaporization tubes.
Another feature of the invention is the provision of a basin at the bottom of the condenser chamber for collecting and draining the water directed onto the bundle of condenser tubes. The basin is configured to guide the downward flow of air smoothly through a 180.degree. turn and back upwardly into the condenser chamber for exhaustion therefrom. The basin is contoured to prevent entrainment of water by the exhausted air. More particularly, the basin has a smooth curved wall portion below the bundle of condenser tubes for receiving water directed thereover, and a vertically rising wall portion against which water is directed by the curved wall portion. Baffle means are provided at the top of the basin to direct the air downwardly, so that air will be forced to flow also through the lower portion of the basin. At least one baffle member protrudes inwardly of the vertically rising wall portion to create a stop for any upwardly moving water.
A further feature of the invention includes support means engaging the bottom of the condenser shell for supporting the shell, with the support means being spaced outwardly from the sides of the basin to permit access to the basin sides for servicing purposes. The support means comprises support beams extending along opposite sides of the basin. The basin includes generally horizontal peripheral lip portions sandwiched between the support beams and the bottom of the condenser shell. Vertical supporting gussets are secured integrally between the basin sides, the support beams and the peripheral basin lip portions.
Still another feature of the invention includes a cool water vacuum pump for exhausting non-condensible gases from the condenser, the pump including cooling water intake means. Means is provided for utilizing the cooling water needed for the vacuum pump as a partial replacement of the amount of water evaporating from the water cascade.
Other objects, features and advantages of the invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings.